After Generate rig, the pole doesn't work. why?
Well, Blenrig has 2 variants of manipulation pole rotation. First is a rotation bone itself (two arrow bone), next is a pole target, witch is hidden by script. And the reason that script always hides the pole target is because it does not use. 

There is a switcher between bone rotation and pole target rotation is in N-panel has name pole_vector:



when it sets to 1, bone rotation disables, and pole target shows. 

To find this switch select Foot_IK bone.